1. Field of the Invention
The present invention relates to a non-contact method of transmitting electric power from a transmitting coil to a receiving coil and in particular to a method of sending data from the receiving coil to the transmitting coil during power transmission, and to a charging stand and device housing batteries, which uses that data transmission method.
2. Description of the Related Art
A battery charging method and device that utilizes magnetic induction to transmit electric power from a transmitting coil to a receiving coil has been developed (refer to Japanese Laid-Open Patent Publication H09 -63655-A (1997) and Japanese Publication of Registered Utility Model Application No. JP 3011829-U). JP H09-63655-A describes a configuration having a charging stand that houses a transmitting coil magnetically excited by a high frequency power supply, and a battery pack that houses a receiving coil magnetically coupled with the transmitting coil. In addition, the battery pack houses circuitry to rectify the alternating current (AC) induced in the receiving coil and supply direct current (DC) to charge the batteries. With this configuration, a battery pack can be placed on the charging stand to charge the battery pack batteries without direct electrical contact.
Further, JP 3011829-U describes a configuration where the battery containing device houses batteries in its lower part, a secondary-side charging adapter is provided below the batteries, and a receiving coil and charging circuit are housed in the secondary-side charging adapter. A charging stand provided with a transmitting coil, which is magnetically coupled with the receiving coil, is also described. The battery containing device with its secondary-side charging adapter is placed on the charging stand to transmit electric power from the transmitting coil to the receiving coil and charge the device batteries.